Methods of forming memory arrays

ABSTRACT

Some embodiments include methods of forming memory arrays. A stack of semiconductor material plates may be patterned to subdivide the plates into pieces. Electrically conductive tiers may be formed along sidewall edges of the pieces. The pieces may then be patterned into an array of wires, with the array having vertical columns and horizontal rows. Individual wires may have first ends joining to the electrically conductive tiers, may have second ends in opposing relation to the first ends, and may have intermediate regions between the first and second ends. Gate material may be formed along the intermediate regions. Memory cell structures may be formed at the second ends of the wires. A plurality of vertically-extending electrical interconnects may be connected to the wires through the memory cell structures, with individual vertically-extending electrical interconnects being along individual columns of the array. Some embodiments include memory arrays incorporated into integrated circuitry.

RELATED PATENT DATA

This patent resulted from a divisional of U.S. patent application Ser.No. 12/624,312, which was filed Nov. 23, 2009 U.S. Pat. No. 8,158,967,and which is hereby incorporated herein by reference.

TECHNICAL FIELD

Integrated memory arrays, and methods of forming memory arrays.

BACKGROUND

An integrated circuit is a miniature electronic circuit that has beenmanufactured across a semiconductor material. Memory storage is one ofthe types of functions that may be achieved by integrated circuitry.Memory storage commonly utilizes large arrays of identical components.

A continuing goal in the fabrication of integrated memory is to increasethe level of integration of memory components, and thus to increase theamount of memory that may be provided across a given amount ofsemiconductor real estate. This can enable large amounts of memory to beprovided across small chips, which can be valuable in numerousapplications, such as, for example, consumer electronics.

It is becoming increasingly difficult to reduce the scale of existingmemory arrays, and thus it would be desired to develop new arrangementsfor memory arrays. It would be further desired for such new arrangementsto be amenable to fabrication with existing technologies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are a diagrammatic three-dimensional view, and adiagrammatic cross-sectional side view, respectively, of an exampleembodiment of an integrated memory array.

FIG. 3 is a diagrammatic cross-sectional side view of a constructionshown at a processing stage of an example embodiment method of forming amemory array.

FIG. 4 is a diagrammatic cross-sectional side view of the constructionof FIG. 3 shown at a processing stage subsequent to that of FIG. 3.

FIG. 5 is a diagrammatic three-dimensional view of a portion of theconstruction of FIG. 4 (specifically, the portion labeled “5” in FIG.4), shown at the processing stage of FIG. 4.

FIGS. 6-15 are diagrammatic three-dimensional views of the portion ofFIG. 5 shown at sequential processing stages of an example embodimentmethod of forming a memory array, with the processing stage of FIG. 6following that of FIG. 5.

FIG. 16 is a diagrammatic three-dimensional view of several of thestructures of FIG. 15 that are hidden from view in the illustration ofFIG. 15.

FIGS. 17-19 are diagrammatic three-dimensional views of the portion ofFIG. 5 shown at sequential processing stages of an example embodimentmethod of forming a memory array, with the processing stage of FIG. 17following that of FIG. 15.

FIG. 20 is a diagrammatic cross-sectional side view along the line 20-20of FIG. 19.

FIG. 21 is a diagrammatic three-dimensional view of the portion of FIG.5 shown at a processing stage subsequent to that of FIG. 19.

FIG. 22 is a diagrammatic cross-sectional side view along the line 22-22of FIG. 21.

FIG. 23 is a diagrammatic three-dimensional view of the portion of FIG.5 shown at a processing stage subsequent to that of FIG. 21.

FIG. 24 is a diagrammatic cross-sectional side view along the line 24-24of FIG. 23.

FIG. 25 is a diagrammatic three-dimensional view of the portion of FIG.5 shown at a processing stage subsequent to that of FIG. 23.

FIG. 26 is a diagrammatic cross-sectional side view along the line 26-26of FIG. 25.

FIG. 27 is a diagrammatic three-dimensional view of the portion of FIG.5 shown at a processing stage subsequent to that of FIG. 25.

FIG. 28 is a diagrammatic cross-sectional side view along the line 28-28of FIG. 27.

FIG. 29 is a diagrammatic three-dimensional view of various conductivestructures of the integrated memory array formed at the processing stageof FIG. 27.

FIG. 30 is a diagrammatic cross-sectional side view of the constructionof FIG. 28, shown at a processing stage subsequent to that of FIG. 28 inaccordance with an example embodiment method for programming memorycells within a memory cell array.

FIG. 31 is a diagrammatic view of a computer embodiment.

FIG. 32 is a block diagram showing particular features of themotherboard of the FIG. 31 computer embodiment.

FIG. 33 is a high level block diagram of an electronic systemembodiment.

FIG. 34 is a simplified block diagram of a memory device embodiment.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Some embodiments pertain to new vertical memory designs suitable forincorporation into integrated circuitry, and to methods of formingvertical memory. The vertical memory may enable higher levels ofintegration to be achieved than can be achieved with conventional planarmemory, and may be suitable for fabrication with existing technologiesso that it may be fabricated with relatively low cost. In someembodiments, the vertical memory utilizes field effect transistor (FET)switching devices gatedly connected with semiconductor material wires,and utilizes data storage structures formed at ends of the wires. Thewires and data storage structures are together comprised by memory unitcells, and such memory unit cells may be vertically stacked to create ahigh density of the memory unit cells across a given region ofsemiconductor real estate. In some embodiments, individual memory unitcells may have feature sizes corresponding to less than or equal to 25nanometers.

Example embodiments of integrated memory arrays, and example methods offorming integrated memory arrays, are described with reference to FIGS.1-30.

FIGS. 1 and 2 show a portion of a construction 10 comprising an examplememory array. The construction is shown in three-dimensional view inFIG. 1. The three primary axes utilized for the coordinate system ofFIG. 1 are shown in the upper left-hand corner of the figure. Thecoordinate system has a first horizontal axis 3 corresponding to an “X”axis, a second horizontal axis 5 corresponding to a “Y” axis, and avertical axis 7 corresponding to a “Z” axis. The three primary axes 3, 5and 7 are orthogonal to one another.

Construction 10 includes a plurality of vertically-spaced,horizontally-extending tiers 12, 14, 16 and 18. Such tiers compriseelectrically conductive lines 20 and 22, with the electricallyconductive lines extending along the horizontal direction of axis 5. Insome embodiments, such lines may be referred to as extending “primarily”along the direction of axis 5 to indicate that there may be minorvariation of the linearity of the lines along such axis.

The electrically conductive lines 20 and 22 may comprise any suitablecompositions or combinations of compositions. In some embodiments, line20 may comprise, consist essentially of or consist of one or more metalsand/or one or more metal-containing compounds. For instance, line 20 maycomprise, consist essentially of, or consist of metal silicide (forinstance, tungsten silicide, tantalum silicide, titanium silicide,cobalt silicide, nickel silicide, etc.). In such embodiments, line 22may comprise conductively-doped semiconductor material, such as, forexample, conductively-doped silicon.

Although the electrically conductive tiers 12, 14, 16 and 18 are showncomprising two adjacent lines 20 and 22 of different conductivematerials, in other embodiments the tiers may comprise only a singleline of conductive material, and in yet other embodiments the tiers maycomprise more than two lines of conductive materials.

Construction 10 also includes a plurality of wires 24-39 joined to thetiers 12, 14, 16 and 18, and extending horizontally along the directionof axis 3. In some embodiments, the wires may be referred to asextending “primarily” along the direction of axis 3 to indicate thatthere may be minor variation of the linearity of the wires along suchaxis.

The wires 24-39 comprise semiconductor material, such as, for example,one or both of silicon and germanium. The wires have first ends 40 (onlylabeled for wire 24) joined to the tiers, and have second ends 42 (onlylabeled for wire 24) in opposing relation to the first ends.

The wires 24-39 are arranged in a two-dimensional array, with one of thedimensions of such array being along horizontal axis 5, and the other ofthe dimensions of the array being along vertical axis 7. Thetwo-dimensional array may be considered to comprise rows alonghorizontal axis 5, and to comprise columns along vertical axis 7.

The tiers 12, 14, 16 and 18 interconnect wires along the rows of thearray (for instance, tier 18 interconnects the wires 24-27 along a rowof the array).

FIG. 2 shows a cross-section along a plane orthogonal to axis 3 of FIG.1 (specifically, along a plane parallel to axis 5 of FIG. 1), and showsthat the wires 24-39 are square-shaped along such cross section. Inother embodiments, the wires may have other shapes along thecross-section of FIG. 2, including, for example, circular, oval,elliptical, rectangular, etc.

Gate dielectric 46 (only some of which is labeled in FIG. 1, but all ofwhich is labeled in FIG. 2) is along outer edges of the wires 24-39. Inthe shown embodiment, the wires have a square cross-sectional shape, andthe gate dielectric is formed along opposing sidewalls of such squareshape. Accordingly, the gate dielectric only partially surrounds theindividual wires. In other embodiments, the gate dielectric may entirelysurround the individual wires.

The gate dielectric 46 may comprise any suitable composition orcombination of compositions, and in some embodiments may comprise,consist essentially of, or consist of silicon dioxide. The gatedielectric may be homogeneous, as shown, or may comprise multipledifferent materials.

Electrically conductive gate material 48 is provided around the wires24-39. In the shown embodiment, the gate material 48 forms a gatestructure 50 that extends primarily in a vertical direction (i.e.,primarily along the axis 7). The gate material 48 is shown contactingthe gate dielectric 46 on two opposing sides of each of wires 24-39. Inother embodiments, the gate dielectric 46 may entirely surround theindividual wires, and the gate material 48 may also entirely surroundthe individual wires.

Although the gate structure is shown comprising a single homogeneousmaterial 48, in other embodiments the gate structure may comprise two ormore different materials. The various materials of gate structure 50 maycomprise any suitable composition or combination of compositions. Insome embodiments, such materials may comprise one or more of variousmetals (for instance, titanium, tungsten, cobalt, nickel, etc.),metal-containing compositions (for instance, metal nitrides, metalsilicides, etc.), and conductively-doped semiconductor materials (forinstance, conductively-doped silicon, conductively-doped germanium,etc.).

The wires 24-39 may be considered to have intermediate regions 44 (FIG.2, and labeled only for wire 24) between the first and second ends 40and 42. The intermediate regions are not labeled in FIG. 1, due to suchregions being hidden by gate structure 50.

Memory cell structures 52 (FIG. 1) are formed at the ends of wires24-39. The memory cell structures may be alternatively referred to asdata storage structures, and may be any structures suitable for storingdata in a memory cell. Although the gate structures are shown to behomogeneous, in some embodiments the gate structures may comprisemultiple different materials.

In some embodiments, the memory cell structures 52 may correspond to onetime programmable structures, resistance RAMS (i.e., memory that changesresistance upon switching; including phase change memory, oxide RAM,etc.), multi-time programmable devices, etc. In some embodiments, thememory cell structures may be antifuse structures; such as, for example,structures of the types described in U.S. Pat. No. 7,210,224, listingJigish D. Trivedi as the inventor, and listing Micron Technology, Inc.as the assignee. In some embodiments, the memory cell structures maycorrespond to MRAM structures; such as, for example, structures of thetypes described in U.S. Pat. No. 7,214,547, listing Joel A. Drewes asthe inventor, and listing Micron Technology, Inc. as the assignee. Insome embodiments, the memory cell structures may be phase change memorystructures; such as, for example, structures of the types described inU.S. Pat. Nos. 7,332,735 and 7,511,984, listing Kristy A. Campbell andJun Liu as the inventors, respectively, and listing Micron Technology,Inc. as the assignee.

If the memory cell structures 52 correspond to antifuse structures, theymay contain a thin layer of dielectric material between a pair ofelectrodes. In operation, sufficient voltage may be passed to break downthe dielectric and thereby cause the electrodes to electrically contactone another. A programming state of a memory cell structure may bedesignated by whether the structure is a blown antifuse, or an antifusewhich is not blown. The memory cell structures 52 are shown to behomogeneous, and in some embodiments may correspond to the thindielectric of antifuse structures. In other embodiments, the memory cellstructures may not be homogeneous, but may instead comprise a pair ofelectrically conductive electrodes having a thin layer of dielectricmaterial therebetween.

If memory cell structures 52 correspond to MRAM structures, then thememory cell structures may comprise a pair of magnetic materials, and anonmagnetic material between the magnetic materials. In operation, theorientation of a magnetic moment in one of the magnetic materials may becompared relative to the orientation of a magnetic moment in the otherof the magnetic materials to determine a programming state of the memorycell structure.

If memory cell structures 52 correspond to phase change memorystructures, then the memory cell structures may comprise phase changematerial, such as, for example, various chalcogenides.

A plurality of cell strings are configured as vertically-extendingelectrical interconnects (specifically, vertically-extending bars) 54,56, 58 and 60 (FIG. 1) that extend along columns of the wires (forinstance, bar 54 extends along a column comprising wires 24, 28, 32 and36), and that electrically connect to the wires through the memory cellstructures 52. The bars 54, 56, 58 and 60 may comprise any suitableelectrically conductive material or combination of materials, and may,for example, comprise one or more of various metals (for instance,titanium, tungsten, cobalt, nickel, etc.), metal-containing compositions(for instance, metal nitrides, metal silicides, etc.), andconductively-doped semiconductor materials (for instance,conductively-doped silicon, conductively-doped germanium, etc.). Thebars 54, 56, 58 and 60 are shown in phantom view in FIG. 1 so that otherstructures are visible through the bars.

The tiers 12, 14, 16 and 18 are shown electrically connected tocircuitry 61-64, respectively; the gate structure 50 is shownelectrically connected to circuitry 65; and the vertical bars 54, 56, 58and 60 are shown electrically connected to circuitry 66-69,respectively. Most of the circuitry is illustrated with boxes, and it isto be understood that the circuitry can be any suitable circuitry. Thecircuitry may be provided in any suitable locations proximate thevarious structures of construction 10. For instance, at least some ofthe circuitry may be under the construction, at least some of thecircuitry may be laterally adjacent the construction, and/or at leastsome of the circuitry may be over the construction. The circuitrycorresponds to logic and wiring utilized to read and/or write from thememory array of construction 10.

An example circuit is shown for circuitry 69. Such example circuitincludes a transistor 70 having a gate 72 and source/drain regions 74and 76. The gate is electrically connected to a row line 78, one of thesource/drain regions is electrically connected to bar 60, and the otherof the source/drain regions is connected to a bitline 80.

The wires 24-39 may be doped so that such wires, in combination withgate structure 50, form a plurality of transistor devices. Specifically,the intermediate regions 44 of the wires may be doped to correspond tochannel regions of the transistor devices, and the ends 40 and 42 of thewires may be doped to correspond to source/drain regions of thetransistor devices. In operation, current passed through gate structure50 may be used to gatedly couple the source/drain regions at the ends ofthe wires to one another through the channel regions in the intermediateportions the wires. The various circuitry 61-69 may be utilized touniquely address individual memory cell structures 52 when current ispassed through gate structure 50. For instance, circuitry 61electrically connects to a memory cell structure 52 at the end of wire24, and circuitry 66 electrically connects to the same memory cellstructure through vertical bar 54. Thus, the circuitries 61 and 66 maybe together utilized to program such memory cell structure and/or toread the programmed state of such memory cell structure. If the memorycell structure is an antifuse device, the programming may compriseproviding a sufficient voltage differential between circuitry 61 andcircuitry 66 to blow the antifuse; and subsequent reading may compriseascertaining if current flow through the memory structure corresponds toa blown or a not-blown antifuse device.

Although construction 10 is shown having gaps between thevertically-spaced tiers 12, 14, 16 and 18, between adjacent wires, andbetween adjacent vertical bars 54, 56, 58 and 60; any suitabledielectric materials may be provided in such gaps to electricallyisolate the various electrical components from one another.

Construction 10 may be formed to be integrated circuitry supported by asemiconductor substrate, and may be formed utilizing any suitablefabrication process. Example processes are described with reference toFIGS. 3-30.

Referring to FIG. 3, a semiconductor construction 100 comprisesalternating layers of first and second materials 102 and 104,respectively. The materials are supported by a substrate 101.

Substrate 101 can comprise, consist essentially of, or consist of, forexample, monocrystalline silicon lightly-doped with background p-typedopant, and may be referred to as a semiconductor substrate. The term“semiconductor substrate” means any construction comprisingsemiconductive material, including, but not limited to, bulksemiconductive materials such as a semiconductive wafer (either alone orin assemblies comprising other materials thereon), and semiconductivematerial layers (either alone or in assemblies comprising othermaterials). The term “substrate” means any supporting structure,including, but not limited to, semiconductor substrates.

The second material 104 is ultimately patterned into wires analogous tothe wires 24-39 of FIG. 1. Accordingly, the second material 104comprises semiconductor material, and in some embodiments may comprise,consist essentially of, or consist of one or both of silicon andgermanium.

In some embodiments, the first material 102 is selectively removablerelative to the second material 104. In such embodiments, materials 102and 104 may both correspond to semiconductor materials, but may differfrom one another in composition and/or doping. For instance, one of thematerials 102 and 104 may comprise silicon and not germanium; while theother comprises germanium and not silicon. As another example, one ofthe materials 102 and 104 may consist of silicon, while the othercomprises, consist essentially of, or consists of a combination ofsilicon with germanium. As yet another example, both of materials 102and 104 may correspond to doped silicon, but one of the materials may bep-type doped and the other may be n-type doped.

In the shown embodiment, barrier material 106 is provided between thematerials 102 and 104. The barrier material may be used to preventdopant from dispersing between layers 102 and 104 in embodiments inwhich a difference between materials 102 and 104 is the dopant typeand/or concentration. In other embodiments, the barrier material may beomitted. The material 106 may comprise any suitable composition, and insome embodiments may be an electrically insulative material. Forinstance, material 106 may comprise, consist essentially of or consistof silicon dioxide.

In some embodiments, the first material 102 is an electricallyinsulative material. For instance, the first material may comprise,consist essentially of or consist of silicon dioxide. The barriermaterial 106 may be omitted in such embodiments, so that materials 102and 104 are stacked directly against one another. In embodiments inwhich material 102 is an electrically insulative material, the material102 may be considered to be in the form of electrically insulativesheets provided between vertically-stacked plates of material 104.

The alternating materials 102 and 104 may be formed over substrate 101with any suitable processing. For instance, the alternating materialsmay be formed by epitaxial growth from over a surface of substrate 101;and/or may be deposited over the surface of substrate 101 utilizingchemical vapor deposition (CVD) and/or atomic layer deposition (ALD). Inembodiments in which barrier material 106 is provided, such barriermaterial may be formed utilizing any suitable processing; including forexample, one or both of CVD and ALD.

In the shown embodiment, materials 102 and 104 are formed within atrench that extends into substrate 101. In other embodiments, materials102 and 104 may be formed across a non-trenched upper surface ofsubstrate 101, rather than within a trench.

Although substrate 101 is shown to be homogeneous, in some embodimentsthere may be circuitry formed across or within substrate 101 prior toforming the alternating materials 102 and 104. For instance, some of thecircuitry 61-69 of FIG. 1 may be provided over or within substrate 101prior to forming the alternating materials 102 and 104.

Referring to FIG. 4, materials 102 and 106 (FIG. 3) are selectivelyremoved relative to material 104 to leave a stack of vertically-spacedplates 108 of material 104. The plates are spaced from one another bygaps 103.

The materials 102 and 106 may be removed by forming openings (not shown)extending through materials 102, 104 and 106, and then providing etchantwithin such openings; with the etchant being selective for materials 102and 106 relative to material 104. Although material 106 is shown to havebeen removed, in other embodiments only material 102 may be removed; andaccordingly materials 104 and 106 may remain at the processing stage ofFIG. 4.

The selective removal of material 102 relative to material 104 maycomprise any suitable processing. In some embodiments, material 102comprises germanium and material 104 consists of silicon; and theremoval of material 102 utilizes one or more of hydrofluoric acid,nitric acid, acetic acid, hydrogen peroxide, ammonium hydroxide, ozoneand HCl. In some embodiments, material 102 comprises p-type dopedsilicon, and material 104 comprises n-type doped silicon, and theselective removal of material 102 utilizes tetramethylammoniumhydroxide.

The shown embodiment has four vertically-spaced plates 108. The numberof vertically-spaced plates may be selected to achieve a desired numberof wires along a column of a memory array of the type shown in FIG. 1;and accordingly may be a number greater than four.

An advantage of forming the alternating materials within the trench isthat the sidewalls of the trench may assist in supporting thevertically-spaced plates 108. In the shown embodiment, thevertically-spaced plates 108 are supported only by the sidewalls of thetrench that the plates have been formed in. In other embodiments,spacers (not shown) may be provided between the plates to support theplates.

FIG. 5 shows a three-dimensional view of a portion of FIG. 4corresponding to the vertically-spaced plates 108 in isolation fromsubstrate 101. The three-dimensional view of FIG. 5 utilizes the samecoordinate system discussed above with reference to FIG. 1, andaccordingly coordinate axes 3, 5 and 7 are shown in the upper left-handcorner of FIG. 5. The remaining FIGS. 6-30 will be shown in isolationfrom substrate 101 in order to simplify the drawings, but it is to beunderstood that the various structures shown in FIGS. 6-30 would besupported by the semiconductor substrate 101.

In embodiments in which material 102 (FIG. 3) comprises an electricallyinsulative material, the processing of FIG. 4 may be omitted, so thatthe insulative material remains between the vertical plates atsubsequent processing steps. Accordingly, in some embodiments, thestructure of FIG. 5 will comprises sheets of insulative material 102within the regions shown as gaps 103 in the figure.

Referring to FIG. 6, a patterned mask 110 is formed over thevertically-stacked plates 108. Mask 110 comprises a plurality offeatures 112 which are spaced from one another by gaps 114. The features112 may be formed from any suitable material; including, for example, ahard mask material (for instance, metal nitride, silicon nitride, etc.).If the features 112 comprise a hard mask material, such material may beformed into the shown pattern by initially forming a uniform layer ofthe material across the upper surface of the top plate 108; then formingphotolithographically-patterned photoresist over the hard mask material,transferring a pattern from the photoresist into the hard mask material,and subsequently removing the photoresist to leave the shownconstruction. In other embodiments, the photoresist may remain over thehard mask material at the processing stage of FIG. 6.

Referring to FIG. 7, gaps 114 are extended through plates 108 (FIG. 6)with a suitable etch; such as, for example, a reactive ion etch. Suchsubdivides the plates into a plurality of planar pieces 116. Spacers,lattices, or other supporting structures (not shown) may be providedbetween and under the plates at various locations, prior to thesubdivision of the plates, to support the various planar pieces.

In embodiments in which the material 102 of FIG. 3 is not removed (i.e.,in the embodiments discussed above with reference to FIGS. 3-5 in whichinsulative material sheets of material 102 remain in the locations shownas gaps 103), the etching of FIG. 7 will be conducted through a stackcomprising alternating materials 102 and 104. Such etching may beconsidered to subdivide the plates 108 (FIG. 6) into planar pieces 116,and to subdivide the insulative material 102 (FIG. 3) into insulativespacers between the planar sheets (the insulative spacers would be inthe locations of gaps 103 in FIG. 7).

Referring to FIG. 8, mask 110 (FIG. 7) is removed, and replaced with anew mask 118. Mask 118 comprises a plurality of features 120 which arespaced from one another by gaps 122. Gaps 122 are wider than the gaps114 (FIG. 6) that had been defined by the previous mask 110 (FIG. 6).Mask 118 may be formed of any suitable material or combination ofmaterials; including, for example, one or both of a hard mask materialand photoresist.

After mask 118 is provided, dopant is implanted through gaps 122 to formimplant regions 124 along sidewalls of the semiconductor material 104 ofthe planar pieces 116. In some embodiments, the dopant may be n-type. Insuch embodiments the implant regions 124 may comprise an “n” dopantlevel or an “n+” dopant level, and in either event will beconductively-doped regions.

After the implant regions 124 are formed, the mask 118 may be removed toleave the construction shown in FIG. 9.

Referring to FIG. 10, insulative material 126 is formed between theplanar pieces 106. The insulative material 126 may comprise any suitablecomposition, and in some embodiments may comprise, consist essentiallyof, or consist of silicon dioxide. Insulative material 126 may be formedwith any suitable processing, including, for example, one or both of CVDand ALD. In embodiments in which material 102 (FIG. 3) is insulativematerial (such as silicon dioxide), and in which the processing of FIG.4 is omitted so that material 102 remains between the planar pieces 116at the processing stage of FIG. 8 (instead of the gaps 103), theinsulative material between the planar pieces may be material 102instead of material 126.

The insulative material 126 forms spacers 128 between the planar pieces116, and also forms a spacer 128 over the uppermost planar piece 116.There may also be insulative material along the bottom of the lowermostplanar piece 116, although such is not shown in FIG. 10. The shownconstruction comprises stacks of alternating materials 104 and 126; oralternatively considered, comprises stacks of alternating planar pieces116 and spacers 128.

The gaps 114 remain between the planar pieces 116 after formation ofinsulative material 126. If the formation of the insulative materialfills or partially fills such gaps, additional masking and etching maybe conducted to re-establish the gaps and form the construction of FIG.10.

After insulative material 126 is formed, construction 100 is subjectedto salicidation conditions to form silicide 130 along outer edges of thedoped regions 124. The silicide 130 forms electrically conductive tiers131 along the sidewall edges of semiconductor material 104, with suchtiers being analogous to those described in FIG. 1 as tiers 12, 14, 16,and 18. The tiers 131 are linear, and extend primarily along thehorizontal axis 5 of the three-dimensional coordinate system shown inthe figures.

The silicide 130 may comprise any suitable composition, and may, forexample, comprise, consist essentially of, or consist of one or more ofcobalt silicide, nickel silicide, titanium silicide, etc.

The salicidation reaction is one of many methods that may be used toform conductive runners along the sidewall edges of the planar pieces116. Another example method is to laterally recess such sidewall edgesto form gaps over the underlying spacers 128, and to then fill such gapswith one or more electrically conductive materials (for instance, one ormore of various metals, metal-containing compositions, andconductively-doped semiconductor materials).

Referring to FIG. 11, a patterned mask 132 (shown in dashed line) isformed over the stack of materials 104/126, and is used to pattern afill within gaps 114 so that the gaps become filled with insulativematerial 134. Insulative material 134 may have any suitable composition,and in some embodiments may comprise, consist essentially of, or consistof silicon dioxide. The insulative material may be deposited within thegaps 114 and over the mask 132, and then chemical-mechanical polishing(CMP), or other suitable processing, may be used to remove theinsulative material from over the mask. In subsequent processing, themask may be removed to leave the construction of FIG. 12. Suchconstruction has rails 135 of material 134 extending above the uppermostsurfaces of the stacks of materials 104/126.

Referring to FIG. 13, masking material 136 is formed over the stackedmaterials 104/126 and patterned into a mask. The patterned mask hassegments 138 extending along rails 135, and has segments 140 extendingorthogonally to the segments 138. The segments 138 and 140 may be formedsequentially relative to one another in some embodiments.

The masking material 136 may be a hard mask material (for instance,metal nitride, silicon nitride, etc.). The material 136 may be formed inthe shown pattern by initially forming a uniform layer of hard maskmaterial across the stacked materials 104/126; then formingphotolithographically-patterned photoresist over the hard mask material,transferring a pattern from the photoresist into the hard mask material,and subsequently removing the photoresist to leave the shownconstruction. In other embodiments, the photoresist may remain over thehard mask at the processing stage of FIG. 13.

Referring to FIG. 14, patterned material 136 is used as a mask during anetch into stacked materials 104/126. Such etch may be any suitable etch;such as, for example, a reactive ion etch.

The etching through material 104 of the planar pieces 116 (FIG. 13)forms lines 142 of the semiconductor material 104, with such linesextending orthogonally to tiers 131; and specifically extending alongthe axis 3 of the three-dimensional coordinate system shown in thefigures. The lines 142 will ultimately be patterned to form wiresanalogous to those described in FIG. 1 as wires 24-39.

Referring to FIG. 15, masking material 136 (FIG. 14) is removed, and theremaining structure is covered with an insulative material 144. Suchinsulative material may, for example, comprise, consist essentially of,or consist of silicon dioxide. In some embodiments, at least some of themasking material 136 may not be removed prior to forming insulativematerial 144. For instance the segments 138 (FIG. 14) of the maskingmaterial that are along rails 134 (FIG. 14) may remain at the processingstage of FIG. 15 in some embodiments.

FIG. 16 shows the arrangement of the various conductive andsemiconductive components at the processing stage of FIG. 15, inisolation from the insulative components of FIG. 15, to assist thereader in visualizing the layout of various structures that are hiddenfrom view in the diagram of FIG. 15.

Referring to FIG. 17, masking material 146 (shown in phantom view) isformed over the insulative material 144. The masking material ispatterned into a plurality of features 148 which are spaced from oneanother by gaps 150. Masking material 146 may comprise any suitablecomposition; including, for example, a hard mask composition.

Referring to FIG. 18, gaps 150 are extended through insulative material144 with one or more suitable etches, and then masking material 146(FIG. 17) is removed.

Referring to FIGS. 19 and 20, gate dielectric 46 (FIG. 20) and gatematerial 48 are formed within gaps 150 (FIG. 18) and over the stackedmaterials 104/126. The gate material may then be subjected toplanarization, for example CMP, to form the shown planarized surface 151extending across materials 48, 134 and 144. The gate dielectric 46 andgate material 48 can be identical to the gate dielectric and gatematerial discussed above with reference to FIGS. 1 and 2. Although thegate dielectric is shown to be homogeneous, in other embodiments (notshown), the gate dielectric may comprise two or more differentmaterials. Also, although only one gate material is shown, in otherembodiments (now shown) multiple gate materials may be utilized.

FIG. 20 shows that the lines formed from the alternating materials 104and 126 (such lines extend in and out of the page relative to thecross-sectional view of FIG. 20) create vertically-extending stacks(with a pair of such stacks being shown in FIG. 20, and being labeled asstacks 145 and 147). Each stack has a pair of opposing sidewalls (theopposing sidewalls of stack 145 are labeled 141 and 143). The gatedielectric 46 extends along and directly against the insulative material126 and the semiconductor material 104 of such sidewalls; and the gatematerial 48 extends along the sidewalls, and is spaced from thesidewalls by the gate dielectric.

Referring to FIGS. 21 and 22, patterned masking material 152 is formedover planarized surface 151. The patterned masking material has openings154-159 extending therethrough. The patterned masking material maycomprise a hard mask composition, and may be patterned utilizingprocessing analogous to that discussed above with reference to FIG. 6for patterning the material of mask 110. The patterned masking materialis utilized during etching through materials 104, 126 and 144. Suchetching extends openings 154-159 through materials 104, 126 and 144 asshown in FIG. 22.

Once that openings 154-159 penetrate through the various lines ofsemiconductor material 104, the lines are broken into segments; witheach segment corresponding to a wire 160. The wires 160 are analogous tothe wires 24-39 discussed above with reference to FIGS. 1 and 2. Each ofthe wires 160 has a first end joined to the tiers comprising silicide130, and a second end in opposing relation to the first end. The secondends of the wires are along the openings 154-159. Some of the first endsof the wires 160 are labeled 161 in the cross-sectional view of FIG. 22,and some of the second ends of the wires 160 are labeled 163 in FIG. 22.The wires 160 also have intermediate regions between the first andsecond ends, with such intermediate regions extending through gatedielectric 46 and gate material 48; analogously to the descriptionprovided above with reference to FIGS. 1 and 2. Some of the intermediateregions are labeled 165 in FIG. 22.

Analogously to the wires 24-39 discussed above with reference to FIGS. 1and 2, the wires 160 may have the intermediate regions 165 doped to bechannel regions of transistor devices (for example, provided with athreshold voltage dopant), and may have the ends 161 and 163 heavilydoped to be source/drain regions. In some embodiments, the doping of theintermediate regions may occur during the initial formation of thesemiconductor material in the stack of FIG. 3, and the doping of ends161 may occur with the heaving doping at the processing stage of FIG. 8.In such embodiments, the doping of ends 163 may occur at the processingstage of FIG. 22 by implanting dopant into openings 154-159 to dope theportions of the wires 160 adjacent such openings. Alternatively, thedoping of the ends 163 of wires 160 may occur at other processingstages, such as, for example, by out-diffusion of dopant from structuresthat are subsequently formed adjacent to the ends 163.

Referring to FIGS. 23 and 24, memory cell material 170 is formed withinopenings 154-159, and along the second ends 163 of wires 160. The memorycell material may be any composition suitable to form memory cellstructures. For instance, if the memory cell structures are to beantifuses, the memory cell material 170 may be dielectric that is to beformed between a first electrode corresponding to an end 163 of a wire160, and a second electrode that will be provided on an opposing side ofthe dielectric from the first electrode.

Although one memory cell material is shown, in some applications theremay be multiple memory cell materials formed within the openings. Forinstance, the memory cell materials may correspond to a stack containinga thin layer of dielectric material sandwiched between a pair ofconductive materials, so that the entire stack is provided as antifusestructures against the ends 163 of wires 160.

In some embodiments, the memory cell material 170 may comprise phasechange material, and may be suitable for forming PCRAM type memorystructures.

In some embodiments, memory cell materials may be provided to comprise anon-magnetic layer sandwiched between a pair of magnetic layers, and maybe suitable for forming MRAM-type memory structures.

The memory cell material 170 forms a uniform lining within openings154-159. Such may be accomplished with any suitable methodology,including, for example, one or more of ALD, CVD and physical vapordeposition (PVD).

Although the memory cell material 170 is shown forming a uniform liningalong the sidewalls of openings 154-159, in other embodiments the memorycell material may be selectively formed only along the exposed ends 163of the wires 160. Such selective placement of the memory cell materialmay utilize any suitable methodology, including, for example, selectiveALD, electroless plating and/or electrolytic plating.

Referring to FIGS. 25 and 26, openings 154-159 (FIGS. 23 and 24) arefilled with electrically conductive material 180. The electricallyconductive material 180 may comprise any suitable composition, and insome embodiments may comprise one or more of various metals (forinstance, titanium, tungsten, cobalt, nickel, etc.), metal-containingcompositions (for instance, metal nitrides, metal silicides, etc.), andconductively-doped semiconductor materials (for instance,conductively-doped silicon, conductively-doped germanium, etc.).Although a single homogenous material 180 is shown filling the openings,in other embodiments (not shown) the openings may be filled withmultiple materials. The one or more materials utilized to fill theopenings may be formed by any suitable method, including, for example,one or more of CVD, ALD and PVD.

Referring to FIGS. 27 and 28, materials 152, 170 and 180 (FIGS. 25 and26) are etched back to about the level of surface 151. Such etchback maybe accomplished with CMP. The memory cell material 170 forms a pluralityof tubes that extend vertically along the ends of wires 160; and theconductive material 180 forms electrically conductive cores within suchtubes. The material 170 forms memory cell structures analogous to thememory cell structures 52 discussed above with reference to FIGS. 1 and2, and the cores formed from conductive material 180 are verticalinterconnects analogous to the bars 54, 56, 58 and 60 discussed abovewith reference to FIGS. 1 and 2.

FIG. 29 shows the arrangement of the various primary components at theprocessing stage of FIGS. 27 and 28, in isolation from some of theinsulative components of FIGS. 27 and 28, to assist the reader invisualizing the layout of various structures that are hidden from viewin the diagram of FIG. 27. Some of the features illustrated in FIG. 29are shown in phantom view so that other features may be seen behindthem. The phantom view is not utilized to indicate importance, or lackthereof, of various features, or to indicate that certain features areoptional. Only some of the various repeating structures of FIG. 29 arelabeled, in order to simplify the drawing.

The embodiment of FIG. 29 is analogous to that of FIG. 1. The wires 160of FIG. 29 are analogous to the wires 24-39 (FIG. 1), and, like thewires 24-39, form two-dimensional arrays containing rows and columns.The conductive lines of material 130 form tiers analogous to the tiers12, 14, 16 and 18 of FIG. 1, and, like the tiers 12, 14, 16 and 18, thetiers of FIG. 29 interconnect rows of wires. The conductive material 180of FIG. 29 forms vertically-extending electrical interconnects, or cellstrings, (specifically, cylindrical rods) analogous to the bars 54, 56,58 and 60 of FIG. 1, and, like such bars, the vertically-extendingelectrical interconnects of FIG. 29 are along columns of the arrays ofwires. The memory cell material 170 of FIG. 29 forms memory cellstructures analogous to the structures 52 of FIG. 1. However, in theembodiment of FIG. 1 the memory cell structures 52 are formed ofmaterials that are only at the ends of the wires, whereas in theembodiment of FIG. 29 the memory cell material 170 extends the fulllength of the vertical interconnects of material 180. The embodiment ofFIG. 29 may be more cost-efficient to manufacture, and may be suitablein applications in which there will not be cross-talk through the memorycell material 170. In other applications, such as when there could becross-talk between adjacent memory cells if the memory cell materialwere continuous between the adjacent memory cells, the embodiment ofFIG. 1 may be more appropriate.

FIG. 29 shows that in some embodiments the cell strings corresponding tothe vertically-extending electrical interconnects (i.e., the rods formedof material 180) may be shared by memory cells on opposing sides of thecell strings. Such may enable high levels of integration to be achieved.

Circuitry analogous to the circuitry 61-70 of FIG. 1 is not shown inFIG. 29, but such circuitry would be present. Various components of suchcircuitry may be in any desired location relative to the construction ofFIG. 29; and accordingly may be below, above, or laterally adjacent theconstruction of FIG. 29.

As discussed previously, the one or more memory cell materials may beprovided to form various types of memory cell structures suitable forstorage of data. In some applications, the memory cell material 170 maycorrespond to a thin layer of dielectric material utilized to formantifuses between the wires 160 and the rods formed of material 180.Data may be stored by either blowing an antifuse (to break down thedielectric and form a conductive contact) or not blowing an antifuse.FIG. 30 shows the construction 100 of FIG. 28 in an application in whichthe memory cell material 170 consists of the thin dielectric materialutilized for antifuses. The construction is shown after programming hasbeen conducted to form some regions 200 of blown antifuses, whileleaving other regions 202 where the antifuses are not blown. The blownantifuses may correspond to one type of data bit, while the not-blownantifuses correspond to a different type of data bit; and thus thearrangement of blown and not-blown antifuses may store information. Suchinformation may be later accessed by using different combinations ofcurrent through various gates, tiers and vertical columns ofconstruction 100 to uniquely address the various memory cells of theconstruction.

The embodiments discussed above may be utilized in electronic systems,such as, for example, computers, cars, airplanes, clocks, cellularphones, etc.

FIG. 31 illustrates an embodiment of a computer system 400. Computersystem 400 includes a monitor 401 or other communication output device,a keyboard 402 or other communication input device, and a motherboard404. Motherboard 404 may carry a microprocessor 406 or other dataprocessing unit, and at least one memory device 408. Memory device 408may comprise an array of memory cells, and such array may be coupledwith addressing circuitry for accessing individual memory cells in thearray. Further, the memory cell array may be coupled to a read circuitfor reading data from the memory cells. The addressing and readcircuitry may be utilized for conveying information between memorydevice 408 and processor 406. Such is illustrated in the block diagramof the motherboard 404 shown in FIG. 32. In such block diagram, theaddressing circuitry is illustrated as 410 and the read circuitry isillustrated as 412.

Processor device 406 may correspond to a processor module, andassociated memory utilized with the module may comprise variousstructures of the types described with reference to FIGS. 1-30.

Memory device 408 may correspond to a memory module, and may comprisevarious structures of the types described with reference to FIGS. 1-30.

FIG. 33 illustrates a simplified block diagram of a high-levelorganization of an electronic system 700. System 700 may correspond to,for example, a computer system, a process control system, or any othersystem that employs a processor and associated memory. Electronic system700 has functional elements, including a processor 702, a control unit704, a memory device unit 706 and an input/output (I/O) device 708 (itis to be understood that the system may have a plurality of processors,control units, memory device units and/or I/O devices in variousembodiments). Generally, electronic system 700 will have a native set ofinstructions that specify operations to be performed on data by theprocessor 702 and other interactions between the processor 702, thememory device unit 706 and the I/O device 708. The control unit 704coordinates all operations of the processor 702, the memory device 706and the I/O device 708 by continuously cycling through a set ofoperations that cause instructions to be fetched from the memory device706 and executed. The memory device 706 may include various structuresof the types described with reference to FIGS. 1-30.

FIG. 34 is a simplified block diagram of an electronic system 800. Thesystem 800 includes a memory device 802 that has an array of memorycells 804, address decoder 806, row access circuitry 808, column accesscircuitry 810, read/write control circuitry 812 for controllingoperations, and input/output circuitry 814. The memory device 802further includes power circuitry 816, and sensors 820, such as currentsensors for determining whether a memory cell is in a low-thresholdconducting state or in a high-threshold non-conducting state. Theillustrated power circuitry 816 includes power supply circuitry 880,circuitry 882 for providing a reference voltage, circuitry 884 forproviding a first interconnection line (for instance, a wordline) withpulses, circuitry 886 for providing a second interconnection line (forinstance, another wordline) with pulses, and circuitry 888 for providinga third interconnection line (for instance, a bitline) with pulses. Thesystem 800 also includes a processor 822, or memory controller formemory accessing.

The memory device 802 receives control signals from the processor 822over wiring or metallization lines. The memory device 802 is used tostore data which is accessed via I/O lines. At least one of theprocessor 822 or memory device 802 may include various structures of thetypes described with reference to FIGS. 1-30.

The various electronic systems may be fabricated in single-packageprocessing units, or even on a single semiconductor chip, in order toreduce the communication time between the processor and the memorydevice(s).

The electronic systems may be used in memory modules, device drivers,power modules, communication modems, processor modules, andapplication-specific modules, and may include multilayer, multichipmodules.

The electronic systems may be any of a broad range of systems, such asclocks, televisions, cell phones, personal computers, automobiles,industrial control systems, aircraft, etc.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

1. A method of forming a memory array, comprising: forming aconstruction comprising vertically-stacked semiconductor materialplates; the plates being vertically spaced from one another by gaps;patterning the plates to subdivide the plates into a plurality of planarpieces having sidewall edges; the planar pieces being verticallystacked; providing insulative material spacers in the gaps; formingelectrically conductive tiers along the sidewall edges of the planarpieces; the electrically conductive tiers being vertically spaced fromone another; etching through the semiconductor material of the planarpieces, and through the insulative material of the spacers, to formlines that extend orthogonally to the electrically conductive tiers;some of the lines being semiconductor material lines, and others of thelines being insulative material lines; forming gate dielectric along thesemiconductor material lines; forming a gate material spaced from thesemiconductor material lines by the gate dielectric; forming openingspassing through the semiconductor material lines to break eachsemiconductor material line into a pair of segments; each segmentpassing through the gate material, having a first end joined to anelectrically conductive tier, and having a second end in opposingrelation to the first end; the segments being arranged as an array thatcomprises vertical columns and horizontal rows; the electricallyconductive tiers extending along the rows of the array of segments;forming memory cell structures at the second ends of the segments; andforming a plurality of vertically-extending electrical interconnectsconnected to the segments through the memory cell structures; individualvertically-extending electrical interconnects being along individualcolumns of the array.
 2. The method of claim 1 wherein the memory cellstructures include phase change material.
 3. The method of claim 1wherein the memory cell structures include magnetic material.
 4. Themethod of claim 1 wherein the memory cell structures are antifusestructures; and further comprising programming some of the memory cellstructures by blowing some of the antifuses.
 5. The method of claim 1wherein the semiconductor material plates are subdivided before theinsulative material is provided in the gaps.
 6. The method of claim 1wherein the insulative material is provided in the gaps before thesemiconductor material plates are subdivided.
 7. The method of claim 1wherein the semiconductor material is a second semiconductor material,and wherein the forming of the vertically-stacked plates comprises:forming alternating layers of first semiconductor material and thesecond semiconductor material, where the first semiconductor material isselectively removable relative to the second semiconductor material; andselectively removing the first semiconductor material relative to thesecond semiconductor material.
 8. The method of claim 7 wherein one ofthe first and second materials comprises p-type doped semiconductormaterial, and wherein the other of the first and second semiconductormaterials comprises n-type doped semiconductor material.
 9. The methodof claim 7 wherein one of the first and second materials comprisessilicon and does not comprise germanium; and wherein the other of thefirst and second semiconductor materials comprises germanium and doesnot comprise silicon.
 10. The method of claim 7 wherein one of the firstand second materials comprises silicon and does not comprise germanium;and wherein the other of the first and second semiconductor materialscomprises both silicon and germanium.
 11. The method of claim 7 wherein:the openings are formed through the insulative material lines, as wellas through the semiconductor material lines, and the forming of theopenings breaks the insulative material lines into insulative materialsegments; the semiconductor material segments and insulative materialsegments together form vertically-extending stacks, with suchvertically-extending stacks having a pair of opposing sidewalls; thegate dielectric is directly against the semiconductor material segmentsalong the opposing sidewalls of the vertically-extending stacks; and thegate material is formed directly against the gate dielectric along theopposing sidewalls of the vertically-extending stacks.
 12. A method offorming a memory array, comprising: forming a stack comprising planarpieces of semiconductor material alternating with insulative materialspacers; forming electrically conductive tiers along sidewall edges ofthe planar pieces; etching through the semiconductor material of theplanar pieces to form semiconductor material lines that extendorthogonally to the electrically conductive tiers; forming gatedielectric along the semiconductor material lines; forming a gatematerial spaced from the semiconductor material lines by the gatedielectric; forming openings passing through the semiconductor materiallines to break each semiconductor material line into a pair of segments;each segment having a first end joined to an electrically conductivetier, and having a second end in opposing relation to the first end; andforming memory cell structures along the second ends of the segments.